Thermalright SI-128 SE Heatsink Review

Overall Score

I was originally running my quad core-based HTPC with its stock intel cooler. When I realized that there was basically no hope of running it at anything other than stock clock, I started looking for a high performance replacement that would fit into my case. Then baligavinod posted this thread, and my search ended. I decided that I was going to buy the SI-128 SE and see how it fared against a Intel Quadcore X3220. When I got back to school, I purchased this fine piece from Xoxide here.



  • Dimensions : L125 x W145 x H91.5 mm (heatsink only)
  • Weight : 510g (heatsink Only)


  • Works optimally with a quiet, low RPM 120mm fan
  • Proprietary thru-holes adopted from the HR-series to increase air flow movement
  • 8mm heatpipes with high heat transfer efficiency
  • Patented support bar design preventing heatsink from deformation over time
  • Increased height of heatsink fins for better motherboard compatibility
  • Fan blow down design helps to cool CPU surrounding


  • INTEL: All Intel P4 LGA775 processors
  • AMD: Intel Socket AM2 Athlon64 / FX / X2 / Opteron

Package Contents:

  • SI-128 SE Heatsink
  • Mini Wrench
  • Multi-Backplate
  • AM2 and 775 mounting hardware
  • Anti-Vibration Strips
  • Thermalright Thermal Paste
  • Instalation Guide

The Package was the typical Thermalright packaging.  Clean brown box with more than ample protection for its precious contents.




She’s not going anywhere.


This is a good shot of the four massive 8mm heatpipes and the “Proprietary thru-holes adopted from the HR-series to increase air flow movement”.


Here is a shot of the ”Patented support bar design preventing the heatsink from deformation over time”.


This is a lot larger than I expected and I was actually starting to worry whether or not it was going to fit in my case. 


The bottom looked really nice.  Very smooth even though you can see the machining marks.  I didn’t notice any concave or convex areas either.


The included hardware:


The pieces needed for a 775 socket installation (minus the 4 screws in the upper right.  Those are actually for the AM2 installation set).


The AM2 components.


The all important, and pretty sweet looking case badge!!!


120mm fan clips, Thermalright Thermal Paste and the Anti-Vibrations strips.

Installing this beast was a little more difficult than I was expecting coming from the TR U120e where it’s just 4 screws that are fairly simple to put in.  The TR SI-128 SE put up a little more of a fight.


This is the Multi-Backplate with 2 of the posts in.  The posts are secured by rubber O-rings that slip into a grove in the post, holding it in the backplate.


This picture shows how the posts sit between 2 raised points to secure the post from spinning when the screws that hold the heatsink bracket are secured.



Here is the mounting bracket on the top side.  Putting it this way shows that there is just enough clearance to get over the voltage regulators.


Now both brackets are on.  The SI-128 SE has the same bracket setup as the Ultima 90.


Like a lot of the other large, aftermarket heatsinks, installation of the SI-128 SE is most easily accomplished with the motherboard out of the case (unless you have really, really small hands).



With the “SilentPipe” heatsink that my Gigabyte P35-DQ6 motherboard has, there wasn’t a whole lot of room to put this baby in.  Here, the two heatsinks are actually touching.  I had to do some playing around to see just which way this would fit.  And now, after I completed all of the testing, I have it mounted a quarter turn clockwise and have actually bent the fins on the top tower of the northbridge heatsink so that the two wouldn’t touch.  The way that it was worked fine, I turned it because if I want to stand the case up, I want the heatpipes to be running horizontally so that they are able to function better.  When The case lays flat, the way the heatpipes run isn’t important.


A look from the other side.  Use of the included “Mini Wrench” is a must as there is no way to get a screwdriver in to tighten the screws down.  I have also noticed that the heatsink does slide around a little if you push on it, but a simple solution would be to place a washer on the top side of the mounting bracket to eat up the extra space.  Note: The movement is not bad by any means.  I just wanted to include it here as an FYI.


Showing the clearance a little more.


Now, it’s back in the case and the rest of the components are joining it.


As you can see, it’s a pretty tight fit in my case, a Gateway G6-200 that I salvaged and gave new life.


This is how the SI-128 SE is situated in my case now.

The Competition:



Intel Stock Cooler


The stock cooler in my case.


Thermalright Ultra-120 Extreme (U120e)


The TR U120e in my case.


Doesn’t quite fit.


A side by side comparison between the sizes of the 3 heatsinks.


The SI-128 SE has about the same dimension as the U120e in terms of the length and number of the radiator fins.


But the SI-128 SE fins are only about half of the size of the U120e’s.


Testing was done in my dorm room where the conditions weren’t exactly clinically controllable, but I worked at the most consistent ambient temperatures possible. The tests were conducted at stock settings with the case closed up to help control how the ambient setting affected it.

The test system:
· CPU – Intel Xeon LGA775 X3220 @ 2.4GHz
· Motherboard – Gigabyte P35-DQ6
· RAM – 2 x 2GB DDR2-800 mushkin
· GPU – EVGA 8600GT
· Storage – Western Digital 250GB
· Optical – Lite-On 20X DVD+/-RW with LightScribe
· TV – Avermedia TV Tuner
· Thermal Compound – Arctic Silver 5

Screen shots were taken after the computer had booted up and had time to cool back down to it’s idle state and then after the idle shot was taken, Prime95 was run for 15 minutes and another screen shot was taken.

The TR U120e and the SI-128 SE were installed with the S-Flex SFF21F 1600RPM, 28.0dBA 120mm fan attached to them.



Stock intel cooler at idle.


Stock intel cooler after 15 minutes of Prime95.


TR U120e at idle.


TR U120e after 15 minutes of Prime95.


TR SI-128 SE at idle.


TR SI-128 SE after 15 minutes of Prime95.


This is with the TR SI-128 SE running 2 instances of the 5.91 SMP Folding client at 3.4GHz.  This is running stable currently.


This is my other system with a Q6600 in it also running at 3.4GHz with very similar settings running 2 instances of the 5.91 SMP Folding client in the same room under the same ambient conditions.  While this isn’t a real official comparison, as these are two different systems, I feel that it shows a decent comparison between the two at this speed.



After seeing the performance of my TR U120e I was very anxious to test the TR SI-128 SE.  I was not expecting it to outperform, or even keep up with the TR U120e but due to Thermalright’s excellent rep, I expected that the TR SI-128 SE would be hands down better than the stock Intel cooler.  All I was really looking for in the SI-128 SE was the ability to run my quad core at 3.0GHz or faster.  The SI-128 SE far surpassed my expectations!!!

Once I got past the hassle I faced during installation and actually saw how well this heatsink performed, I was very pleased with this product.  While my tests may not have been the most intensive, or the most thorough, they do show that the SI-128 SE can definitely hold its own in the cooling business.  The difference between the surface area provided for cooling in the SI-128SE and the U120e is very little.  There is a difference between the TR U120e and the SI-128 SE in the number and diameter of heatpipes.  The TR U120e has six, 6mm heatpipes where the SI-128 SE only has four heatpipes, but they are 8mm.  I believe that the size difference, along with the limited air flow in my older case, allowed the SI-128 SE to run right alongside the TR U120e in terms of performance.  I am truly amazed at how well it did perform.  For those of you that are going to be using this in a more modern HTPC case, you might not see as impressive of a performance in your system, but how many of you are going to be running quads in your HTPC, or even OC them to 3.4GHz for that matter?  I mean, let’s be rational, that’s a little more than is needed right?  I truly believe that the SI-128 SE will keep any dual core at a more than reasonable temperature.

The lower profile of the heatsink will allow it to fit into more cases than its big brother, the U120e, and the fan blowing down onto the CPU and northbridge will definitely help cool not only of the CPU and northbridge but also the components around the CPU.  However, the size of the SI-128 SE could be an issue so check to make sure that it fits in your case – it almost didn’t in mine.

And for a final note, at a regular price of $53.99 at, it is a great way to save a couple bucks and not sacrifice much performance when you are building a PC or looking for a new heatsink.  I would definitely recommend this heatsink!!!

Discuss in the forums.


  • Facebook
  • Twitter
  • Myspace
  • Google Buzz
  • Reddit
  • Stumnleupon
  • Delicious
  • Digg
  • Technorati

Leave A Response